1. Technical Field
The present invention relates to free space optical switching, and more particularly to apparatus for switching optical signals between waveguides of planar lightwave circuits.
2. Description of the Related Art
Free-space micro electromechanical systems (MEMS) optical switches have been found to offer a number of advantages including high port count, low insertion loss, low crosstalk, optical transparency, and polarization insensitivity. However, practical application of prior art switch designs is often limited because of alignment issues, assembly issues, and size issues due to the bulk optical elements and long free-space propagation distances.
Planar lightwave circuits (PLCs) have proven to be a convenient platform for fabricating components of lightwave communication systems. PLCs offer the advantages of precise manufacturing, small form factor, simple packaging and thermal stabilization.
Compact optical switches can be realized by combining MEMS devices and PLCs. Prior art MEMS-PLC based optical switch designs, however, typically only offer small port counts (1×2 or 2×2) without cascading multiple switches (which raises crosstalk and loss issues), or employ complex designs requiring the use of multiple mirrors in the optical signal path, which gives rise to manufacturing and alignment issues.